Abstract: A multi-function yo-yo switchable between operation as a traditional yo-yo, a free-spin yo-yo, and a centrifugal-clutch yo-yo. Within one or both of the fly disks is one or more rotational-speed governors, and about the axle is a cylindrical axle sleeve which is rotatable about the axle. Each governor is spring-biased to an inwards position the governor contacts the axle sleeve, forcing the axle sleeve to rotate with the fly disks and axle. However, when the yo-yo spins sufficiently rapidly, the governors are thrown by centrifugal force to a radially-outwards position so as not to be in contact with the axle sleeve so that the axle sleeve may rotate independently of the fly disks. A function control switch locks the governors in the inwards position or the outwards position or allows the position to be controlled by centrifugal force.

Abstract: A method of optimizing a portfolio includes selecting an investment universe with a finite number of assets, forming a belief matrix based on one or more homogeneous inequality relationships among the expected returns of assets in the universe, selecting those asset returns that are consistent with the belief matrix to form a consistent set of return vectors, selecting a set of allowable weight vectors for the assets in the universe, determining a centroid vector of the consistent set of return vectors with respect to a probability measure, and finding an optimal portfolio by finding a weight vector on a boundary of the set of allowable weight vectors that maximizes an inner product with the centroid vector.

Abstract: A play object consisting of a larger ball with an open, substantially spherical-section cavity into which a smaller ball fits snuggly, yet is easily removable and re-insertable due to the diameter of the rim of the cavity being slightly smaller than the diameter of the smaller ball. The rim of the cavity is rounded. When the smaller ball is positioned in the cavity, it protrudes to roughly the spherical boundary defined by the larger ball to allow the combination to roll. When the smaller ball is removed from the cavity, the smaller ball is rollable, and the larger ball is relatively stable when placed on a flat surface with the cavity side down. Furthermore, multiple larger balls oriented with the cavity side downwards may be stacked. The balls are preferably soft, and their surfaces can be smooth, ribbed or furry. Ribbed larger balls provide the advantages of facilitating stacking, and obscuring deviations in the trueness of rolling produced by the lip of the cavity.

Abstract: A swinging bob toy having two bobs constrained to, yet slidable along, a string. Each end of the string has a pair of low-mass, spaced-apart stoppers which allows the end of the string to be easily grasped so that smooth transitions can be made between various modes of operation. The string is smooth enough and thick enough that it slides over the fingers and wrists with a minimum of friction and abrasion. The even number of bobs on the string allows for configurations with a symmetrical weight distribution so that one bob may act as an exact counterweight to the other bob.

Abstract: A swinging bob toy having an outer bob and middle bob on a string, with the middle bob having a bore through which the string passes to allow the middle bob to slide along the string. The middle bob has a substantially toroidal, liquid-containing bladder. The mass of the liquid contributes substantially to the overall mass of the middle bob, but the viscosity of the liquid and the dimensions of the bore of the toroid are such that the dynamic moment of inertia (i.e., a moment of inertia dependent on linear and/or rotational velocity and/or acceleration, of a history thereof) is small as the middle bob begins its rotation as the outer bob passes the top of its orbit.

Abstract: An ultra-wideband, large-current radiator consisting of a ground plane and two electric monopoles: a wide radiating monopole orthogonal to the ground plane, and a thin monopole orthogonal to the ground plane and normally displaced from the wide monopole. The frequency-independent low impedance of the antenna allows a small voltage to generate a large current. The wide radiating monopole may be a flat sheet, or a sheet of parallel bars. Shielding by the wide monopole suppresses radiation from the thin monopole into a sector of space into which the monopole radiation characteristic of a well-formed impulse in response to a voltage step is desired. In one preferred embodiment, two parallel flat sheets or a conducting cylinder is used as the wide radiating monopole, further shielding radiation from the thin monopole.

Abstract: A swinging bob toy having a middle bob with a non-cylindrically symmetric internal structure. The center of mass is located near the middle of the bore axis, and the percentage azimuthal variation V in the moment of inertia I about an axis in the equatorial plane, given by V=100×[I(&phgr;max)−I(&phgr;min)]/I(&phgr;max), is minimized, for instance by positioning the internal components to produce a weight distribution with n-fold symmetry, where n≧3. In one preferred embodiment, the bobs are equipped with lights powered by on-board batteries. Flat cylindrical batteries are mounted on an equatorial circuit board with their axes of symmetry perpendicular to the bore axis. To allow battery replacement, the top and bottom halves of each bob are removably attached by screw-secured posts parallel to, but offset from, the bore axis. An on/off switch is accessible via a small aperture through a transparent outer shell.

Abstract: A pickup-bed cover prop having an elongated base, a pair of straps attached to the base, a pair of struts extending orthogonally from the base, and a clamp on each strut at the end distal from the end attached to the base. Each strut includes a mechanism which allows the length of the strut to be adjusted and secured. The prop is secured to the truck bed by lowering the rear gate of the pickup bed, passing the straps through the space between the rear edge of the bed and the bottom of the gate, aligning the base of the prop with the rear edge of the bed, and closing the gate, thereby securing the straps due to pressure applied to the straps by the rear edge of the bed and the bottom of the gate. The orientation of the cover is secured by clamping the clamps to the rear end of the cover, and adjusting and securing the lengths of the struts.

Abstract: Methods for increasing the imaging accuracy of object density pixel values by forming linear combinations thereof to counteract spatial mixing of object density pixel value information, and by using an estimate of the object density pixel values to correct for the effects of variations in the object density. A measured variable M as a function of time t is related to the actual object density by M(t)=∫F((q),q,t) (q) dq, where q is the spatial variable. An estimated object density * is related to an actual object density by (q)=∫&Sgr;tE([],q,t)F(,q′,t) (q′) dq′, where E is an approximate inverse of F, and &Sgr;tE([],q,t)F(,q′,t) is defined as the kernel function A(q,q′). Due to the limited number of time samples, the kernel A only approximates the delta function &dgr;(q−q′), and values of (q′) away from q=q′ contribute to *(q).